JP2010026516A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique of reducing variations in temperature of a heating member for heating a material to be heated while reducing heat capacity of the heating member, with respect to a fixing device for an image forming apparatus. <P>SOLUTION: The fixing device has a heating member having diamond fine particles dispersed at least in its surface layer, a pressing member which comes in press contact with the heating member and nips and carries a sheet in collaboration with the heating member, and a heating unit which heats the heating member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing device in an image forming apparatus, and more particularly, to a technique for reducing temperature variation of a heating member that heats a sheet that is a heated material in the fixing device.

  2. Description of the Related Art Conventionally, a fixing layer, a fixing belt, and the like of a fixing device are formed with a release layer for preventing toner from adhering to the fixing roller and an elastic layer for adjusting the flexibility of the surface of the fixing roller. ing.

  Resins are mainly used as materials for these release layers and the like, but usually resins have lower thermal conductivity than metals. For this reason, when temperature variation occurs in the release layer or the like that forms the surface of the fixing roller or the like, it takes time to eliminate the temperature variation. If the toner is fixed while the temperature varies in the circumferential direction or the axial direction of the fixing roller or the like, unevenness in gloss or color of the fixed toner is caused.

  This variation in the temperature of the fixing roller or the like is noticeable particularly when a heating member such as the fixing roller having a small heat capacity is used in order to save energy. That is, when the heat capacity of the heating member is small, for example, when a sheet such as paper passes through the nip portion of the fixing roller or the like, the surface temperature of the fixing roller or the like immediately decreases.

  However, the release layer and the elastic layer have low thermal conductivity, and it takes time to raise the temperature. Therefore, the fixing process is performed without returning to the original temperature. As a result, the temperature at the time of fixing varies. As described above, when the temperature of the fixing roller or the like does not return to the temperature necessary for fixing the toner at the time of pressure contact, and the temperature of the roller varies, the fixing performance of the toner is lowered. As a result, in order to maintain the fixing performance, a certain heat capacity is required, and it has been difficult to reduce both the heat capacity of the fixing member and the variation in temperature.

 An object of an embodiment of the present invention is to provide a technique for reducing variation in temperature of a heating member while reducing a heat capacity of a heating member that heats a heated material in a fixing device of an image forming apparatus.

  In order to solve the above-described problem, a fixing device according to one embodiment of the present invention includes a heating member in which diamond fine particles are dispersed and contained in at least a surface layer, a sheet that is in pressure contact with the heating member, and cooperates with the heating member. A pressure member that sandwiches and conveys the heating member, and a heating unit that heats the heating member.

  The fixing device further includes a temperature-uniforming member that contains a dispersion of diamond fine particles in a surface layer in contact with the heating member to reduce temperature variation of the heating member.

  Further, the surface layer of the soaking member is formed by dispersing diamond fine particles having an average particle size of 0.1 μm or more and 500 nm or less in a fluororesin.

  In addition, a fixing device according to another aspect of the present invention includes a soaking roller having a diamond-like carbon layer on a surface thereof, and a plurality of rollers including the soaking roller, and the rotation of the plurality of rollers. An endless fixing belt whose belt surface moves with the belt, a pressure roller which presses against the belt surface of the fixing belt and cooperates with the belt surface to sandwich and convey the sheet, and heats the fixing belt And a heating unit.

  According to the present invention, in the fixing device of the image forming apparatus, it is possible to reduce the temperature variation of the heating member while reducing the heat capacity of the heating member that heats the material to be heated.

1 is a cross-sectional view of a fixing device provided in an image forming apparatus according to a first embodiment. In Embodiment 1, it is the result of having measured the temperature of the release layer of the paper passing part and the non-paper passing part when the sheet is continuously passed. In Embodiment 1, it is the result of measuring the temperature of the release layer immediately before passing paper and the temperature of the release layer at a position immediately before reaching the nip portion after passing paper. FIG. 6 is a cross-sectional view of a fixing device according to a modification of the first embodiment. FIG. 6 is a cross-sectional view of a fixing device according to a second embodiment. 6 is a partial cross-sectional view of a fixing roller of Embodiment 2. FIG. It is the result of measuring the temperature of the release layer immediately before passing the paper and the temperature of the release layer at the position immediately before reaching the nip portion again after passing the paper. It is the top view which looked at the induction heating apparatus of Embodiment 2 from the arrow A direction of FIG. It is the front view which looked at the induction heating apparatus of Embodiment 2 from the arrow B direction of FIG. FIG. 6 is a cross-sectional view of a fixing device according to a third embodiment. FIG. 6 is a cross-sectional view of a fixing device according to a fourth embodiment. It is sectional drawing of the soaking | uniform-heating roller of Embodiment 4. 6 is a graph showing a temperature distribution of the fixing belt according to the working mobile phone 4;

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a fixing device 1 provided in the image forming apparatus according to the first embodiment.

  The fixing device 1 is a device for fixing toner formed on a sheet P such as paper or an OHP sheet onto a sheet P as a material to be heated by heat.

  The fixing device 1 includes a fixing roller 2 as a heating member, a pressure roller 3 as a pressure member, a peeling claw 5, a thermistor 6 as a contact temperature sensor, a thermostat 10, and an excitation as a heating unit. The coil 11 is provided. The fixing device 1 is in contact with a fixing roller 2 that is driven to rotate in the direction of arrow R by a drive motor (not shown), and a pressure roller 3 that rotates in the direction of arrow R ′ following the fixing roller 2. By passing the sheet P having unfixed toner adhered to the surface thereof through the nip portion N, the toner can be melted and pressed against the sheet P to fix the image on the sheet P.

  Hereinafter, each configuration of the fixing device 1 will be described.

  As described above, the fixing roller 2 is a heating member for melting the toner. When the sheet P is passed through, the fixing roller 2 is heated to a constant temperature to melt the toner. Further, the fixing roller 2 is rotationally driven in the direction of arrow R by a drive motor (not shown) as described above. The fixing roller 2 of this embodiment is configured by laminating a release layer 7 on the outer surface of a cored bar 8. The diameter of the fixing roller 2 is, for example, 30 mm.

  The metal core 8 is a cylindrical member made of iron and having a thickness of 0.5 mm. In addition to iron, stainless steel, aluminum, or a composite material of stainless steel and aluminum may be used. In addition, an eddy current is generated on the cored bar 8 by the magnetic flux generated in the exciting coil 11 which is an induction heating device described later, and the cored bar 8 generates heat due to electric resistance. The fixing roller 2 is heated by the heat generated by the cored bar 8.

  The release layer 7 is a layer having releasability for preventing the toner from adhering to the fixing roller 2 and fixing the toner to the sheet. The release layer 7 of this embodiment is formed by dispersing diamond fine particles in a fluorine-based resin such as PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) or PTFE (polytetrafluoroethylene). is there.

  The thickness of the release layer 7 of this embodiment is 5 μm. The diamond fine particles added to the fluororesin have an average particle diameter of about 300 nm and are dispersed at a ratio of 3 wt% with respect to the release layer 7. Here, in the present embodiment, the maximum diameter of each diamond fine particle is used as the particle diameter, and the average particle diameter is obtained by photographing diamond fine particles with an electron microscope, and randomly extracting 500 diamond fine particles from the photographed image. The value obtained from the average value of the particle diameters of the extracted diamond fine particles.

  By dispersing the diamond fine particles in the release layer 7, the wear resistance of the release layer 7 can be improved. In the case of a conventional release layer made of only a fluororesin, the wear resistance is low, so that it gradually wears due to friction with the thermistor 6 that is a contact-type temperature detection unit and friction with the passing sheet P. . Therefore, in order to ensure the life of the fixing roller, the release layer needs to have a thickness of about 20 μm to 50 μm. In contrast, the release layer 7 of the present embodiment can have a thickness of 5 μm due to improved wear resistance. By making the thickness of the release layer 7 as thin as 5 μm, the heat capacity of the release layer 7 can be reduced.

  Furthermore, the thermal conductivity of diamond is 2000 W / K to 3300 W / K, and the thermal conductivity is higher than that of a normal fluororesin. Therefore, the thermal conductivity of the release layer 7 can be greatly improved by dispersing the diamond fine particles in the release layer 7. Since the thermal conductivity can be improved and the heat capacity can be reduced, the temperature variation in the axial direction of the release roller 7 and the temperature variation in the circumferential direction of the release layer 7 can be suppressed.

  Here, FIG. 2 shows the A4-R paper by the fixing roller 2 of the present embodiment and a conventional fixing roller in which diamond fine particles are not dispersed in order to evaluate the occurrence of a temperature difference in the axial direction of the fixing roller. The result of having measured the temperature of a paper passing part and a non-paper passing part when passing is continuously shown is shown.

  As shown in FIG. 2, in the case of the fixing roller 2 of the present embodiment, the temperature rise of the non-sheet passing portion relative to the sheet passing portion is suppressed to about 20 ° C. On the other hand, in the case of the conventional fixing roller, the temperature difference was 40 ° C. When fixing is performed through the sheet P in a state where a temperature difference exceeding 20 ° C. is generated in the axial direction of the fixing roller, the gloss of the toner fixed at the portion fixed at the high temperature portion and the portion fixed at the low temperature portion. This is not preferable because there is a difference in color or color unevenness. Conventionally, in order to eliminate such a temperature difference, it has been necessary to change the output of a heat source for heating the fixing roller 2 between a high temperature portion and a low temperature portion of the roller, or to provide a heat equalizing heat pipe. However, according to the present embodiment, since the temperature difference is suppressed, such a need is not required.

  FIG. 3 is a graph for evaluating the temperature recovery performance in the circumferential direction of the fixing roller 2 of the present embodiment and a fixing roller having a conventional release layer (contained only of fluororesin, thickness of 30 μm). The results of measuring the temperature of the release layer immediately before passing the paper and the temperature of the release layer at a position immediately before reaching the nip again after passing the paper are shown.

  As shown in FIG. 3, in the case of the release layer 7 of the present embodiment, the temperature drop from the temperature just before passing through the paper to just before passing again after passing once was 2 ° C. On the other hand, in the case of the conventional release layer, the temperature drop was 7 ° C. Therefore, in the case of the present embodiment, it can be understood that the temperature recovery after the sheet passing is quick and the temperature variation in the circumferential direction of the fixing roller 2 is small. When the temperature drop in the circumferential direction is large, for example, when toner is fixed on one sheet by two rotations of the fixing roller, the first turn is fixed at a high temperature, but the second turn is a reduced temperature. Will be fixed. When such temperature variation occurs, a difference in the gloss of the fixing toner or color unevenness occurs in one sheet. According to the release layer 7 of the present embodiment, the temperature variation in the circumferential direction can be reduced, so that gloss unevenness and color unevenness of the toner do not occur.

  Thus, by dispersing diamond in the release layer 7, it is possible to improve the wear resistance and improve the thermal conductivity. And since the mold release layer 7 can be formed thinly by improvement in abrasion resistance, the heat capacity of the mold release layer 7 can be made small. Thereby, the warm-up time can also be shortened.

  Moreover, since the thermal conductivity of the release layer 7 is improved and the thickness is thin, the thermal resistance of the release layer 7 is reduced. As a result, heat is quickly transferred from the metal core 8 to the surface of the release layer 7, and even if the temperature of the release layer 7 is lowered, the temperature can be immediately restored to the temperature required for fixing. Therefore, the variation in temperature distribution in the axial direction of the fixing roller 2 and the variation in temperature distribution in the circumferential direction can be improved. By eliminating the temperature variation, the gloss and color of the toner fixed on the sheet P do not vary, and the image quality of the formed image can be improved.

  The diamond fine particles are preferably added to the release layer 7 in the range of 0.02 wt% to 60 wt%. When the amount of the diamond fine particles is increased, the thermal conductivity of the release layer 7 is improved. However, since it becomes brittle, it is preferable to disperse so as not to exceed 60 wt%. However, if the brittleness can be eliminated by a binder or the like, it is possible to increase the amount of dispersion and further improve the wear resistance. On the other hand, if the amount of dispersion is less than 0.02 wt%, the effect of improving the wear resistance is small, and the release layer 7 cannot be thinned, which is not preferable.

  The average particle size of the diamond fine particles is preferably 0.1 nm or more and 500 nm or less. If it is out of this range, it is not uniformly dispersed, which is not preferable in terms of operability.

  The thickness of the release layer 7 is preferably 3 μm or more and 10 μm or less. If it is thinner than 3 μm, it is difficult to form a layer having a uniform thickness, and if it is thicker than 10 μm, the heat capacity of the release layer 7 is increased.

  Next, the pressure roller 3 is pressed against the fixing roller 2 by the pressure mechanism 4 so as to maintain a constant nip width with the fixing roller 2, and sandwiches the sheet P in cooperation with the fixing roller 2. Transport. The pressure roller 3 rotates in the direction of the arrow R ′ following the fixing roller 2 that is driven to rotate. By passing the sheet P through the nip portion N with the fixing roller 2, the melted toner on the sheet P is pressed and fixed to the sheet P.

  The pressure roller 3 of the present embodiment has a diameter of 30 mm, and is configured by covering the core metal with silicone rubber or fluorine rubber. The silicone rubber or fluororubber layer functions as an elastic layer, and the roller surface is deformed by being pressed against the fixing roller 2 to form a constant nip width. As a result, the heat of the fixing roller is reliably transmitted to the toner of the sheet P passing therethrough, and a satisfactory fixing process is performed.

  Next, the exciting coil 11 is an induction heating device for heating the fixing roller 2. The exciting coil 11 is disposed on the inner periphery of the fixing roller 2, and a magnetic flux is generated by applying a high-frequency alternating current to the exciting coil 11 from an exciting circuit (not shown). An eddy current is generated in the cored bar 8. The cored bar 8 in which the eddy current is generated generates heat due to its electric resistance, and the fixing roller 2 is heated.

  The exciting coil 11 of this embodiment is composed of a litz wire obtained by bundling a plurality of wires that are insulated from each other by covering a copper wire having a diameter of 0.5 mm with an insulating film. By using the litz wire, the diameter of the coil wire can be made smaller than the penetration depth of the current, and an alternating current can be effectively passed. As a material for the insulating coating, polyamideimide having heat resistance is used. A high-frequency current in the range of 20 to 100 kHz can be passed through the exciting coil 11. Moreover, the output can be adjusted from 300 W to 1500 W by adjusting the drive frequency of the excitation circuit.

  In addition, the exciting coil 11 of the induction heating apparatus of this embodiment does not use the core material used in order to concentrate the magnetic flux of a coil, but is made into the air core coil. By using an air-core coil, it is not necessary to use a core material having a complicated shape, so that the cost can be reduced. In addition, the excitation circuit is also inexpensive.

  Next, the configuration of other devices will be described. The peeling claw 5 is a member that is disposed downstream of the nip portion N between the fixing roller 2 and the pressure roller 3 in the rotation direction R and peels the sheet P from the fixing roller 2. The thermistor 6 is disposed downstream of the nip portion of the fixing roller 2 in the rotation direction R and on the side of the fixing roller 2, and detects the temperature of the fixing roller 2. The thermostat 10 is a device that is disposed upstream of the nip portion of the fixing roller 2 in the rotation direction R and detects a temperature abnormality of the fixing roller 2.

  Next, a modification of the first embodiment will be described with reference to FIG. FIG. 4 is a cross-sectional view of a fixing device 1 ′ according to a modification of the first embodiment. The fixing device 1 ′ in FIG. 4 is different from the fixing device 1 of the first embodiment in that toner is fixed by a fixing belt 100 that is an endless belt and a pressure roller 105. The fixing belt 100 is provided with a release layer 100a in which diamond fine particles are dispersed. In such a belt-type fixing device 1 ′, the same effect as that of the roller-type fixing device 1 described above can be obtained. Hereinafter, the configuration of the fixing device 1 ′ according to this modification will be described.

  The fixing device 1 ′ includes a fixing belt 100, a driving roller 101, a driven roller 102, an excitation coil 103 of an induction heating device, and a pressure roller 105.

  The fixing belt 100 is configured by laminating a release layer 100a made of a polyimide film on the outside of a conductive layer 100b for generating an eddy current by a magnetic flux generated by the exciting coil 103. The fixing belt 100 is wound around a driving roller 101 and a driven roller 102 and is driven in the direction of arrow R by the rotation of the driving roller 101.

  The release layer 100a of the fixing belt 100 is composed of a polyimide film in which diamond fine particles are dispersed. The diamond fine particles have an average particle diameter of 300 nm, and 3 wt% is added and dispersed in the release layer 100a of the polyimide film. The release layer 100a has a thickness of 30 μm.

  As described above, the conductive layer 100b is a layer heated by a dielectric heating device. In the present embodiment, the conductive layer 100b is formed by applying Ni to the polyimide film of the release layer 100a. The thickness is 20 μm. As the conductive layer 100b, other conductive materials such as silver and copper can be used.

  The drive roller 101 is driven by a drive motor (not shown) so as to drive the fixing belt 100 in the arrow R direction. Further, the driven roller 102 is urged in a direction opposite to the driving roller 101 by a tension mechanism such as a tension spring (not shown) so as to give a constant tension to the fixing belt 100. Accordingly, the fixing belt 100 can be driven without slipping with respect to the driving roller 101.

  The exciting coil 103 is an induction heating device that heats the fixing belt 100 based on the same principle as the exciting coil 11 described above. That is, a high frequency current is passed through the exciting coil 103 by an exciting circuit (not shown) to generate a magnetic flux, thereby generating an eddy current in the conductive layer 100b of the fixing belt 100. When the eddy current is generated, the conductive layer 100b generates heat due to electric resistance, and the fixing belt 100 is heated.

  The pressure roller 105 is a roller that forms a nip portion N at a position facing the exciting coil 103 with the fixing belt 100 interposed therebetween. The pressure roller is pressed against the fixing belt 100 by a pressure mechanism (not shown), and forms a nip portion N having a constant nip width with the fixing belt 100. The pressure roller 105 may be a rigid roller or a roller having an elastic layer.

  According to the above fixing device 1 ′, the diamond fine particles are dispersed in the polyimide film constituting the release layer 100 a of the fixing belt 100, so that the wear resistance and the thermal conductivity are improved. By improving the wear resistance, the thickness of the polyimide film of the fixing belt 100 can be reduced and the heat capacity can be reduced. Thereby, the warm-up time can be shortened. When the heat capacity is reduced, a temperature difference between the part through which the sheet passes and the part through which the sheet does not pass easily occurs. However, since the thermal conductivity is improved by dispersing the diamond fine particles, such temperature unevenness is reduced. It can be solved in time. Therefore, according to the fixing device 1 ′ of the modified example, it is possible to perform a good fixing process without causing uneven gloss or uneven color due to uneven temperature of the fixing belt 100.

(Embodiment 2)
Next, Embodiment 2 will be described. FIG. 5 is a cross-sectional view of the fixing device 30 according to the second embodiment.

  The fixing device 30 according to the present embodiment is different from the fixing device 1 according to the first embodiment in that an induction heating device 40 for heating the fixing roller 32 is disposed not outside the fixing roller 32 but outside the fixing roller 32. Is different. Further, since the induction heating device 40 is outside the fixing roller 32, the internal structure of the fixing roller 32 is also different. Note that the description of the configuration common to the fixing device of Embodiment 1 is omitted.

  Hereinafter, the configuration of the fixing device 30 according to the second embodiment will be described.

  The fixing device 30 includes a fixing roller 32, a pressure roller 33, a peeling blade 36, a temperature detection unit 38, a thermostat 39, an induction heating device 40, and the like.

  As with the fixing roller of the first embodiment, the fixing roller 32 passes the sheet P on which unfixed toner is adhered to the nip portion N formed by the pressure roller 33 that is in pressure contact, so that the toner is heated by heat. The toner melted and melted by the pressure of the nip portion N is pressed and fixed to the sheet P.

  The configuration of the fixing roller 32 of this embodiment will be described with reference to FIG. FIG. 6 is a partial cross-sectional view of the fixing roller 32 of the present embodiment. The fixing roller 32 is configured by laminating a core metal 35a, a foam rubber layer 35b, a metal conductive layer 35c, an elastic layer 35d, and a release layer 35e in this order from the inside.

  The core metal 35a is a cylindrical core material made of stainless steel and having a thickness of 2 mm.

  The foamed rubber layer 35b is made of a foamable silicone sponge having a thickness of 5 mm and having heat insulation and heat resistance. This foamed rubber layer 35 b is a layer for imparting flexibility to the fixing roller 32 so that a certain nip width is formed between the foamed rubber layer 35 b and the pressure roller 33. Further, since the foamed rubber layer 35b has a heat insulating property, the heat of the metal conductive layer 35c heated by the induction heating device 40 is prevented from being transmitted to the inside of the fixing roller 32, and the thermal efficiency of the fixing roller 32 is increased. Can be increased. In addition, the rubber hardness of the foamed rubber layer 35b of this embodiment is 20 degrees with an Asker C hardness meter.

  The metal conductive layer 35 c is a layer for generating heat and heating the fixing roller 32 by an eddy current generated by a change in magnetic flux generated from the induction heating device 40. Although it performs the same function as the cored bar 8 of the first embodiment, in the case of the present embodiment, the exciting coil of the induction heating device 40 is outside the fixing roller 32, so that the metal is separated from the cored bar 35a. The conductive layer 35c is provided. The metal conductive layer 35c of this embodiment is a Ni layer having a thickness of 40 μm.

  The elastic layer 35d is a layer for adjusting the flexibility of the release layer 35e on the roller surface. By adjusting the flexibility by this layer, the surface of the fixing roller 32 accurately follows the unevenness of the toner on the sheet P at the nip portion N with the pressure roller, and the toner can be heated uniformly. By uniformly heating the toner, the toner fixed on the sheet P does not have uneven gloss, and a good image can be formed.

  The elastic layer 35d of this embodiment is made of silicone rubber in which diamond fine particles are dispersed, and is a layer having a thickness of 200 μm. By adding diamond fine particles having high thermal conductivity, the thermal conductivity of the elastic layer 35d can be improved. The average particle diameter of the diamond fine particles is 300 nm, and 3 wt% is dispersed in the elastic layer 35d.

  The release layer 35e is the same layer as the release layer 7 of Embodiment 1, and is a fluororesin layer having a thickness of 5 μm in which diamond fine particles are dispersed.

  Thus, by dispersing the diamond fine particles in the elastic layer 35d and the release layer 35e, the thermal conductivity of the elastic layer 35d and the release layer 35e can be improved as described above. Further, similarly to the first embodiment, the wear resistance of the release layer 35e constituting the surface of the fixing roller 32 can be improved.

  On the other hand, when the diamond fine particles are not dispersed, since the thermal conductivity of the elastic layer 35d and the release layer 35e is small, it takes time for the heat of the metal conductive layer heated by induction heating to reach the roller surface. It was over. Further, when the output of the induction heating device 40 is increased in order to shorten the heating time, the thermal conductivity of the elastic layer 35d and the release layer 35e is low, so that the temperature difference with the metal conductive layer 35c increases, and the metal conductive layer 35c. And the elastic layer 35d may peel off. Therefore, it has been difficult to shorten the warm-up time.

  However, in the present embodiment, since the thermal conductivity of the elastic layer 35d and the release layer 35e in which the diamond fine particles are dispersed is improved, the temperature of the metal conductive layer 35c, the elastic layer 35d, and the release layer 35e. The difference can be reduced. When the temperature difference is small, peeling of the adhesive layer is prevented, the output of the induction heating device 40 can be increased, and the warm-up time can be shortened.

  Further, by dispersing the diamond fine particles in the elastic layer 35d and the release layer 35e, the temperature variation in the circumferential direction and the axial direction of the surface of the fixing roller 32 can be reduced.

  Here, FIG. 7 shows a fixing roller 32 according to the present embodiment, a fixing layer having a conventional release layer (only composed of fluororesin, thickness 50 μm) and an elastic layer (consisting only of silicone rubber, thickness 200 μm). For the roller, in order to evaluate the temperature recovery performance in the circumferential direction, the temperature of the release layer immediately before passing the paper and the temperature of the release layer at the position immediately before reaching the nip portion after passing the paper are measured. Show.

  As shown in FIG. 7, when the elastic layer 35d and the release layer 35e of the present embodiment are provided, the temperature drop at the position immediately before passing the paper once after passing the paper once from the temperature of the release layer immediately before passing the paper is It was 3 ° C. On the other hand, in the case of a conventional fixing roller having a release layer and an elastic layer to which diamond fine particles are not added, the temperature decrease was 10 ° C.

  Thus, according to the fixing roller 32 of the present embodiment, the thermal conductivity of the elastic layer 35d and the release layer 35e is improved, and the variation in the temperature in the circumferential direction can be improved. Accordingly, it is possible to prevent gloss unevenness and color unevenness of the fixing toner due to temperature unevenness in the circumferential direction and improve image quality.

  Further, according to the fixing roller 32 of the present embodiment, since the diamond fine particles are dispersed, the temperature variation in the axial direction of the fixing roller 32 can also be improved. As will be described later, the induction heating device 40 of the present embodiment controls the heat generation area of the fixing roller 32 so that the exciting coil is located near the center of the fixing roller 32 in order to cope with continuous fixing processing of small-sized sheets. Is divided into a coil 41 that heats the coil and coils 42a and 42b that heat the vicinity of the ends. Therefore, the portion of the fixing roller 32 corresponding to the joint portion between the central coil 41 and the coils 42a and 42b at both ends is difficult to be heated. However, the fixing roller 32 according to the present embodiment has a higher thermal conductivity than the conventional one. It has improved. Therefore, the heat of the heated portion is easily diffused to the portion that is difficult to be heated, and the temperature variation in the axial direction is reduced. Therefore, even if the excitation coil is divided, uneven gloss of the toner fixed in the corresponding portion does not occur.

  Further, the release layer 35e has improved wear resistance and improved thermal conductivity, so that the thickness can be reduced (5 μm in this embodiment). As a result, the roller surface is more flexible than when the release layer 35e is thick as in the prior art (for example, 20 μm to 50 μm), and heat is uniformly transmitted to the toner, so that the image quality can be improved.

  The average particle diameter of the diamond fine particles dispersed in the elastic layer 35d is preferably 0.1 nm to 500 nm. If it is out of this range, it is not uniformly dispersed and it is not preferable in terms of operability.

  As another configuration, a separation blade 36 for separating the sheet P from the fixing roller 32 is disposed downstream of the nip portion N of the fixing roller 32 in the rotation direction R. Further, a separation claw 37 for separating the sheet P from the pressure roller 33 is also arranged downstream of the nip portion of the pressure roller 33 in the rotation direction R ′.

  Further, a temperature detection device 38 that detects the temperature of the fixing roller 32 is disposed further downstream in the rotational direction R of the peeling blade 36. In the present embodiment, as shown in FIG. 9 described later, two temperature detection devices 38 are arranged in the axial direction of the fixing roller 32. By detecting the distribution of the surface temperature of the fixing roller 32 by the temperature detection device 38 and adjusting the output of the induction heating device 40, the temperature in the axial direction of the fixing roller 32 can be controlled.

  A thermostat 39 for detecting an abnormality in the surface temperature of the fixing roller 32 is disposed upstream of the nip portion of the fixing roller 32 in the rotation direction R and on the side of the fixing roller.

  Next, the induction heating device 40 will be described based on FIGS. 8 and 9. 8 is a plan view of the induction heating device 40 as seen from the direction of arrow A in FIG. 5, and FIG. 9 is a front view as seen from the direction of arrow B in FIG. 5 (however, the peeling blade 36 and the peeling claw 37 are shown). Etc. are not shown). As described above, the induction heating device 40 is a device that heats the roller by generating a magnetic flux by the coil to generate heat in the metal conductive layer 35c of the fixing roller 32 as in the case of the exciting coil of the first embodiment. . In the present embodiment, the induction heating device 40 is installed above the fixing roller 32. The excitation coil of the induction heating device 40 is divided into a coil 41 that heats the vicinity of the center of the fixing roller 32 and coils 42a and 42b that heat the vicinity of both ends, and the heating coil is heated according to the size of the passing sheet. It is possible to change the region. For example, if the length in the longitudinal direction of the coil 41 is made to correspond to the length of the short side of A4-R, a high-frequency current is passed only through the coil 41 when the A4-R is continuously fed, and the fixing roller Only the region corresponding to 32 coils 41 can be heated. Thereby, it is possible to prevent the temperature of the region where the sheet P of the fixing roller 32 is not passing from being excessively increased.

  The wires of the coils 41, 42a, and 42b of the present embodiment are the same as those of the first embodiment. In the induction heating device 40 of the present embodiment, the coil is wound around the magnetic core 43 so that the coil characteristics can be sufficiently exhibited even if the number of turns of the coil is reduced. The width of each core 43 is 15 mm, and the interval between the cores is 5 mm. If the interval between the cores is excessively widened, it causes temperature unevenness in the axial direction of the fixing roller 32. Therefore, in this embodiment, the thickness is set to 5 mm.

  As in the first embodiment, the induction heating device 40 generates a magnetic flux when a high frequency current is applied by an excitation circuit (inverter circuit) (not shown).

  As described above, according to the fixing device 30 of the present embodiment, since the diamond fine particles are dispersed in the elastic layer 35d and the release layer 35e, the thermal conductivity of the elastic layer 35d and the release layer 35e can be improved. it can. Further, the wear resistance of the release layer 35e can be improved.

  This makes it possible to reduce the thickness of the release layer. When the layer thickness is reduced, the hardness of the surface of the fixing roller 32 can be reduced, so that heat is uniformly applied to the toner and the image quality of the color image can be improved.

  Further, since the release layer 35e is thin, the heat capacity is reduced, and the thermal conductivity of the elastic layer 35d and the release layer 35e is improved, so that the warm-up time is shortened, and the axial direction and the circumference of the fixing roller 32 are reduced. Variation in temperature in the direction is reduced.

  Further, since the temperature difference between the metal conductive layer 35c and the elastic layer 35d is also reduced, the output of the induction heating device 40 can be increased as compared with the conventional one, and the warm-up time can be shortened.

(Embodiment 3)
Next, Embodiment 3 will be described. FIG. 10 is a cross-sectional view of the fixing device 70 according to the third embodiment.

  The fixing device 70 according to the third embodiment is provided with a temperature-uniforming roller 71, and diamond fine particles are not formed on the elastic layer 75d or the release layer 75e of the fixing roller 75 but on the layer constituting the surface of the temperature-uniforming roller 71. It is different from the above-described embodiment in that it is distributed. Hereinafter, the configuration of the fixing device 70 of Embodiment 3 will be described. Note that description of points common to the first and second embodiments is omitted.

  The soaking roller 71 is a member that eliminates temperature unevenness mainly in the axial direction of the fixing roller 75. The temperature-uniforming roller 71 is moved in contact with the fixing roller 75 while rotating to move heat from the fixing roller 75. Thereby, the heat transfer in the axial direction of the fixing roller 75 can be promoted, and the temperature variation of the fixing roller 75 can be eliminated.

  The soaking roller 71 is configured by laminating a core metal 72 and a release layer 73 in order from the inside.

  The core metal 72 is an aluminum pipe having an outer diameter of 20 mm and a wall thickness of 2.5 mm.

  The release layer 73 formed on the outer side of the cored bar 72 is a layer for preventing a minute amount of toner remaining on the surface of the fixing roller 75 from adhering to the soaking roller 71. The release layer 73 is a 5 μm thick layer made of a fluororesin in which diamond fine particles are dispersed. The diamond fine particles to be added have an average particle diameter of 300 nm and are dispersed by 3 wt% with respect to the release layer 73.

  By dispersing the diamond fine particles in the release layer 73 of the soaking roller 71, the thermal conductivity of the roller surface of the soaking roller 71 can be increased. As a result, heat conduction from the fixing roller 75 to the soaking roller 71 occurs quickly, and temperature unevenness of the fixing roller 75 can be effectively eliminated.

  On the other hand, when the cored bar is in direct contact with the fixing roller without laminating the release layer on the temperature-uniforming roller, the metal cored bar has a high thermal conductivity, so that the effect of eliminating the temperature unevenness of the fixing roller is high. However, a release layer is formed on the roller surface of the fixing roller, and the toner is more likely to adhere to the metal between the metal and the release layer. For this reason, when the release layer is not formed on the temperature-uniforming roller, the toner remaining on the fixing roller adheres to and accumulates on the temperature-uniforming roller. The portion where toner is deposited on the surface of the temperature-uniforming roller has a low thermal conductivity. As a result, the thermal conductivity of the temperature-uniforming roller is decreased, and the heat transfer from the fixing roller 75 is uneven. Absent. In order to remove the toner accumulated on the surface of the temperature-uniforming roller, a cleaning mechanism can be provided, but this is not preferable because the apparatus becomes large. Therefore, it is necessary to form a release layer on the surface of the temperature-uniforming roller.

  However, even when a release layer is provided on the temperature-uniforming roller, when a release layer of fluororesin is simply provided, the release layer has a thickness of 15 μm to 15 μm in consideration of wear due to contact with the fixing roller 75. It is necessary to provide about 50 μm. Since the thermal conductivity of fluororesin is lower than that of metal, the provision of a release layer having such a thickness lowers the soaking effect.

  On the other hand, in the case of the soaking roller 71 of the present embodiment, since the diamond fine particles are dispersed in the release layer 73 as described above, the wear resistance is high, and the thickness of the release layer 73 is increased. It can be formed as thin as 5 μm. Furthermore, since the diamond fine particles have high thermal conductivity and the thickness of the release layer 73 can be reduced to 5 μm, the thermal conductivity of the temperature-uniforming roller 71 can be improved. Therefore, according to the soaking roller 71 of the present embodiment, the soaking effect of the fixing roller 75 can be remarkably improved.

  Further, since no toner adheres due to the release layer 73, a special cleaning mechanism for the temperature-uniforming roller 71 is not necessary. Accordingly, the fixing device 70 and the image forming apparatus including the fixing device 70 can be downsized.

  The other structure of this embodiment is demonstrated.

  The fixing roller 75 includes a cored bar 75a, a foam rubber layer 75b, a metal conductive layer 75c, an elastic layer 75d, and a release layer 75e. The basic configuration of the fixing roller 75 and the function of each layer are the same as those of the fixing roller 32 of the second embodiment, but the point that diamond particles are not dispersed in the elastic layer 75d and the release layer 75e is different from the second embodiment.

  The elastic layer 75d is a layer having a thickness of 200 μm made of only silicone rubber.

  The release layer 75e is a layer having a thickness of 30 μm made of only a fluororesin. The release layer 75e of the fixing roller 75 of the present embodiment is thicker than the release layer 35e (5 μm) of the second embodiment in consideration of wear since diamond fine particles are not dispersed.

  According to the fixing device 70 of the present embodiment described above, it is possible to improve the wear resistance and thermal conductivity of the soaking roller 71. By improving the thermal conductivity of the soaking roller 71, temperature irregularities in the axial direction of the fixing roller 75 can be effectively eliminated even if diamond fine particles are not dispersed in the release layer or the elastic layer of the fixing roller 75. Can do. Accordingly, gloss unevenness and color unevenness of the toner fixed on the sheet P can be reduced, and a high-quality image can be formed.

(Embodiment 4)
Next, a fourth embodiment will be described. FIG. 11 is a cross-sectional view of the fixing device 80 according to the fourth embodiment.

  The fixing device 80 includes a heating member including a fixing roller 81 and a fixing belt 82, a temperature-uniforming roller 83, a pressure roller 84, an induction heating device 85 as a heating unit, a thermopile 86, and a peeling blade 87. And a peeling claw 88 and the like.

  The fixing device 80 of the present embodiment is a device that fixes toner on the sheet P by passing the sheet P on which unfixed toner is adhered through a nip portion N between the endless fixing belt 82 and the pressure roller 84. .

  Hereinafter, each configuration of the fixing device 80 will be described with reference to FIG.

  First, a configuration relating to a heating member that heats the toner on the sheet P in order to fix the toner to the sheet P will be described. In the heating member of this embodiment, the metal conductive layer 82a of the fixing belt 82 is heated by the magnetic flux generated by the induction heating device 85, and the heat passes through the nip portion N where the fixing belt 82 and the pressure roller 84 are in pressure contact. The toner adhering to the sheet P to be heated is heated.

  The fixing roller 81 is a roller around which the fixing belt 82 is wound together with the temperature-uniforming roller 83, and rotates the fixing belt 82 in the arrow R direction following the pressure roller 84 driven by a motor (not shown). The fixing roller 81 of this embodiment has a diameter of 50 mm, a core metal 81 a having a thickness of 2 mm, and a foamed rubber layer 81 b having a thickness of 5 mm laminated on the outside thereof.

  The fixing belt 82 is a heating member that heats and melts the toner on the sheet P by the heat generated from the metal conductive layer 82 a by the induction heating device 85. The fixing belt 82 is wound around the fixing roller 81 and the soaking roller 83 while maintaining a constant tension. A nip portion N is formed at the pressure contact position between the fixing belt 82 and the pressure roller 84. The fixing belt 82 is configured by laminating a metal conductive layer 82a, an elastic layer 82b, and a release layer 82c.

  The metal conductive layer 82 a is a layer for generating heat and heating the fixing belt 82 due to an eddy current generated by a change in magnetic flux generated from the induction heating device 85. The metal conductive layer 82a is a nickel layer having a thickness of 40 μm. As the material of the metal conductive layer 82a, a metal such as stainless steel, aluminum, or a composite material of stainless steel and aluminum can be used in addition to nickel.

  The elastic layer 82b is a layer for imparting flexibility to the fixing belt 82 so as to form a constant nip width with the pressure roller 84. The elastic layer 82b of this embodiment is a silicone rubber layer having elasticity and a thickness of 200 μm.

  The release layer 82 c is a layer that forms a belt surface that is an outer peripheral surface of the fixing belt and prevents toner from adhering to the fixing belt 82. The release layer 82c of this embodiment is a layer of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) having a thickness of 50 μm. In addition, a fluorine-based resin such as PTFE (polytetrafluoroethylene) can be used as the material.

  The soaking roller 83 is a member that eliminates temperature unevenness in the axial direction of the fixing belt 82. The temperature equalizing roller 83 removes temperature unevenness of the fixing belt 82 by moving heat from the fixing belt 82 by coming into contact with the fixing belt 82 and promoting heat movement in the axial direction of the fixing belt 82. Can do.

  The soaking roller 83 is configured by laminating a heat pipe 83a, a metal pipe 83b, and a DLC layer 83c formed by coating diamond-like carbon (hereinafter referred to as DLC) in order from the inside. .

  The heat pipe 83 a is a heat transfer member for making the temperature difference in the axial direction of the temperature equalizing roller 83 uniform. The heat pipe 83a is a copper heat pipe having an outer diameter of 16 mm.

  The metal pipe 83b is an aluminum pipe having an outer diameter of 17 mm and a wall thickness of 0.5 mm. In addition, iron, copper, stainless steel, etc. can also be used as a material.

  The heat pipe 83a and the metal pipe 83b are joined by inserting the heat pipe 83a into the metal pipe 83b and applying heat. FIG. 12 shows a cross-sectional view of the heat pipe 83a inserted into the metal pipe 83b before heat is applied. Before heat is applied, there is a gap S between the heat pipe 83a and the metal pipe 83b. When the temperature-uniforming roller 83 is heated to about 300 ° C. from this state, the heat pipe 83a and the metal pipe 83b expand in the outer diameter direction. And since both have a different linear expansion coefficient, when it returns to normal temperature, the said clearance gap S will disappear and it will be in the combined state. By such a connection, the heat pipe 83a and the metal pipe 83b are in close contact with each other without any gap, and the contact thermal resistance at the boundary between them can be reduced. Therefore, the temperature difference generated in the axial direction of the metal pipe 83b transmitted from the fixing belt 82 is quickly transmitted to the heat pipe 83a, and heat is transmitted from the high temperature portion to the low temperature portion in the heat pipe 83a, so that the heat is made uniform. Thereby, the temperature difference of the soaking roller 83 can be made uniform in the axial direction. Therefore, according to the temperature equalizing roller 83 of the present embodiment, temperature unevenness in the axial direction of the temperature equalizing roller 83 that occurs on the fixing belt 82 can be quickly eliminated.

  In addition, it is preferable that the said heating temperature for eliminating the clearance gap S is 300 degrees C or less based on the heat-resistant temperature of the heat pipe 83a. This is because if the temperature exceeds 300 ° C., the air in the heat pipe 83a expands and the pipe may crack.

  The DLC layer 83 c is a layer for preventing the surface of the temperature-uniforming roller 83 from being worn by contact with the fixing belt 82. The DLC layer 83c of the present embodiment is formed by coating DLC with a thickness of 1 μm on the surface of the metal pipe 83b. The DLC layer 83c is formed by ionized vapor deposition in a high vacuum. DLC is a hard film for material surface modification mainly composed of carbon, has a smooth surface structure, and has excellent wear resistance. Therefore, by forming the DLC layer 83 c on the surface of the temperature-uniforming roller 83, the rotational slidability between the temperature-uniforming roller 83 and the fixing belt 82 can be improved. As a result, it is possible to prevent the metal conductive layer 82 a inside the fixing belt 82 and the surface of the temperature-uniforming roller 83 from being worn. The DLC layer 83c has a thermal conductivity of about 40 W / mK, which is higher than that of a fluororesin (for example, about 0.5 to 0.8 W / mK in the case of PFA). Therefore, according to the DLC layer 83c, it is possible to ensure wear resistance and slidability without impairing the excellent heat transfer performance of the soaking roller 83.

  On the other hand, when the metal pipe 83b and the fixing belt 82 are brought into direct contact without forming the DLC layer 83c, the metal metal pipe 83b has a higher thermal conductivity than the DLC layer 83c. Is obtained. However, when the metal pipe 83b made of aluminum and the metal conductive layer 82a made of nickel inside the fixing belt 82 come into contact with each other, the aluminum pipe 83b having low hardness is worn. Aluminum scraped from the metal pipe 83b adheres to the metal conductive layer 82a. However, when aluminum adheres, the magnetic coupling characteristics between the exciting coil 85a of the induction heating device 85 and the fixing belt 82 change. If the magnetic coupling characteristics change, the mutual inductance changes and power fluctuations occur, or the amount of current flowing through the exciting coil 85a increases, which may reduce the efficiency of induction heating. Conversely, when the metal pipe 83b is made of a metal having a hardness higher than that of nickel, the metal conductive layer 82a is worn, which is not preferable.

  Further, by forming a fluororesin layer such as PFA on the surface of the temperature-uniforming roller, wear due to contact between metals can be prevented, and sliding property is also good. However, a layer using a fluororesin or the like is not preferable because the thermal conductivity is low as described above and the soaking effect of the soaking roller is impaired.

  Here, in FIG. 13, when A4-R paper having a width shorter than the axial length of the temperature equalizing roller 83 of the fixing belt 82 is continuously passed through the fixing device 80 and fixing is performed. The temperature distribution of the fixing belt 82 is shown. DLC in FIG. 13 is the temperature distribution of the fixing belt 82 including the DLC layer 83c of the present embodiment, and the temperature distribution of the fixing belt having a PFA fluororesin layer formed on the surface. As can be seen from the graph of FIG. 13, it can be seen that the fixing belt 82 of this embodiment has a smaller temperature difference between the A4-R paper passing area and the non-A4-R paper passing area. Therefore, according to the soaking roller 83 of this embodiment, the fixing belt 82 can be soaked effectively. On the other hand, in the case of a fluororesin layer, since the heat transfer efficiency from the fixing belt to the soaking roller is lower than that in the present embodiment, the temperature difference between the paper passing area and the non-paper passing area is large. The heat mobility of the soaking roller cannot be fully utilized.

  Furthermore, another advantage of providing the DLC layer 83c on the temperature-uniforming roller 83 is that the DLC layer 83c can be formed at a temperature lower than the heat resistant temperature of the heat pipe 83a. The DLC layer is formed by ionized vapor deposition in a high vacuum, and the temperature during film formation is usually 200 ° C. or lower. Since the heat resistant temperature of the heat pipe 83a is about 300 ° C. as described above, the DLC layer can be formed at a temperature lower than the heat resistant temperature. Therefore, even when the DLC coating process is performed in a state where the heat pipe 83a is inserted into the metal pipe 83b, the heat pipe 83a is not cracked. On the other hand, when a fluororesin layer is provided as a layer on the roller surface, the temperature of the fluororesin coating processing is usually 380 ° C. Therefore, the heat pipe 83a may be cracked, which is not preferable.

  The thickness of the DLC layer 83c is preferably 1 μm or more and 5 μm or less. In order to ensure wear resistance, the thickness is preferably 1 μm or more, and if it is thicker than 5 μm, the heat mobility of the soaking roller is impaired.

  Next, the pressure roller 84 is pressed against the fixing belt 82 between the fixing roller 81 and the belt surface by a pressure mechanism 84a so as to maintain a constant nip width with the fixing belt 82, and cooperates with the belt surface. Then, the sheet P is nipped and conveyed. The pressure roller 84 is rotationally driven in the direction of arrow R ′ by a drive motor (not shown). As a result, the fixing belt 82 and the fixing roller 81 are rotated in the direction of arrow R following the pressure roller 84. By passing the sheet P through the nip portion N with the fixing belt 82, the toner melted by the fixing belt 82 is pressed against the sheet P by the pressure of the pressure roller 84.

  The pressure roller 84 of the present embodiment has a diameter of 50 mm, and is configured by covering the cored bar with silicone rubber or fluorine rubber. The silicone rubber or fluororubber layer functions as an elastic layer, and the roller surface is deformed by being pressed against the fixing belt 82 and the fixing roller 81 to form a constant nip width. As a result, the heat of the fixing roller is reliably transmitted to the toner of the sheet P passing therethrough, and a satisfactory fixing process is performed.

  The induction heating device 85 includes an exciting coil 85 a and a magnetic core 85 b and is disposed on the outer periphery of the fixing belt 82. The induction heating device 85 generates a magnetic flux by a high-frequency current applied to an exciting coil 85a from an unillustrated excitation circuit (inverter circuit). Then, an eddy current is generated in the metal conductive layer 82a of the fixing belt 82 by the change of the magnetic flux, and the metal conductive layer 82a in which the eddy current is generated generates heat due to electric resistance. The fixing belt 82 can be heated by the heat generated by the metal conductive layer 82a.

  The exciting coil 85a is formed by winding a litz wire in which a plurality of wires each having a surface of a copper wire having a diameter of 0.5 mm covered with an insulating material are bundled. As the litz wire of this embodiment, a bundle of 16 copper wires coated with heat-resistant polyamideimide was used as an insulating material. By using the litz wire, the diameter of the coil wire can be made smaller than the penetration depth of the current, and an alternating current can be effectively passed.

  In the present embodiment, a high frequency current can be applied to the exciting coil 85a in the range of 20 to 100 kHz. Further, the output of the induction heating device 85 can be adjusted from 200 W to 1500 W by adjusting the drive frequency of an excitation circuit (not shown).

  The thermopile 86 detects the temperature of the fixing belt 82. Based on the temperature of the fixing belt 82 detected by the thermopile 86, the current from the excitation circuit is adjusted to control the temperature of the fixing belt 82. As a result, the temperature of the fixing belt 82 is maintained at a temperature necessary for fixing the toner.

  The peeling blade 87 and the peeling claw 88 are members for separating the sheet P from the fixing belt 82 and the pressure roller 84, respectively, disposed downstream of the nip portion in the conveyance direction of the sheet P.

  According to the fixing device 80 of the present embodiment described above, since the DLC layer 83c is formed on the soaking roller 83, the excellent wear resistance and slidability of the DLC layer 83c make it possible for the soaking roller 83 to Wear and scraping between the roller surface and the metal conductive layer 82a of the fixing belt 82 are prevented. Further, since the DLC layer 83c has a high thermal conductivity, the contact thermal resistance between the temperature equalizing roller 83 and the fixing belt 82 hardly increases due to the provision of the DLC layer 83c. Therefore, the wear resistance can be improved without impairing the heat transfer characteristics of the soaking roller 83. Accordingly, it is possible to effectively reduce the temperature variation of the fixing belt and realize a fixing process with good image quality without gloss unevenness and color unevenness.

  Furthermore, since the coating processing temperature of the DLC layer 83 is 300 ° C. or lower, it is lower than the heat resistance temperature of the heat pipe 83a of the temperature-uniforming roller 83, and the heat pipe is not damaged in the bonding process between them.

  In the present embodiment, the DLC layer 83c is formed on the roller surface of the soaking roller 83, but the present invention is not limited to this. Any material can be used in place of the DLC layer 83c as long as the temperature during the coating process is lower than the heat resistant temperature of the heat pipe and the material has high wear resistance and thermal conductivity. For example, a tafram film may be formed by Tafram (registered trademark) treatment. The tafram film is a film in which a fine fluororesin is combined with a hard alumite that is hard and excellent in mechanical strength and rich in fine irregularities such as microcracks by a tafram process.

  Tafram film is a high-performance composite film that demonstrates the effects of both hard anodized and fluororesin, and has mechanical properties such as improved wear resistance, improved slidability, anti-galling, and reduced stick-slip. Also, the processing temperature is within 100 ° C., and there is no problem with the heat resistance of the heat pipe. In the case of the tufram process, the soaking roller uses aluminum as in the case of this embodiment. In the case of a tafram film, a sufficient life performance of the heat equalizing roller can be ensured by forming a 20 μm film.

  In this embodiment, the heat pipe is inserted into the temperature-uniforming roller 83, but a DLC layer or the above-mentioned tuffum film may be formed outside a single metal pipe.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications, various improvements, alternatives and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Fixing device, 2 fixing roller, 3 pressure roller, soaking roller, 5 peeling claw, 6 thermistor, 7 release layer, 8 core metal, 10 thermostat, 11 exciting coil, R arrow, N nip part, P Sheet, S gap, 30 fixing device, 32 fixing roller, 33 pressure roller, 35a cored bar, 35b foamed rubber layer, 35c metal conductive layer, 35d elastic layer, 35e release layer, 36 peeling blade, 37 peeling claw, 38 Temperature detector, 39 Thermostat, 40 Induction heating device, 41 Coil, 42a Coil for heating near both ends, 42b Coil for heating near both ends, 43 Magnetic body core, 55e Release layer, 70 Fixing device, 71 Uniformity Heating roller, 72 core metal, 73 release layer, 75 fixing roller, 75a core metal, 75b foam rubber layer, 75c metal conductive layer, 75d Elastic layer, 75e release layer, 80 fixing device, 81 fixing roller, 82 fixing belt, 82a metal conductive layer, 82b elastic layer, 82c release layer, 83 soaking roller, 83a heat pipe, 83b metal pipe, 84 heating Pressure roller, 85 induction heating device, 86 thermopile, 87 peeling blade, 88 peeling claw, 100 fixing belt, 100a release layer, 100b conductive layer, 101 driving roller, 102 driven roller, 103 exciting coil, 105 pressure roller.

JP-A-8-278713

JP-A-9-104964

JP 2005-183122 A

Claims (14)

A heating member in which diamond fine particles are dispersed and contained in at least the surface layer;
A pressure member that press-contacts the heating member and sandwiches and conveys the sheet in cooperation with the heating member;
A heating unit for heating the heating member;
A fixing device.   The fixing device according to claim 1, wherein a release layer in which the diamond fine particles are dispersed is formed on a surface layer of the heating member.   The fixing device according to claim 2, wherein the release layer is formed by dispersing the diamond fine particles in a fluororesin.   The fixing device according to claim 2, wherein the heating member is a fixing roller in which the release layer is formed around a cylindrical core member.   The fixing device according to claim 4, wherein the fixing roller includes an elastic layer having elasticity between the release layer and the core member.   The fixing device according to claim 5, wherein the elastic layer contains diamond fine particles dispersedly.   The fixing device according to claim 6, wherein the elastic layer is formed by dispersing the diamond fine particles in silicone rubber.   The fixing device according to claim 2, wherein the heating member is a fixing belt in which the release layer is formed on an outer peripheral surface of an endless belt including a conductive layer.   The fixing device according to claim 1, wherein the heating member is heated by electromagnetic induction heating.   The fixing device according to claim 9, wherein the heating member includes at least one conductive layer, and the conductive layer is heated by electromagnetic induction heating.   2. The fixing device according to claim 1, further comprising a heat-equalizing member that reduces dispersion in temperature of the heating member, in which diamond fine particles are dispersed and contained in a surface layer in contact with the heating member. A soaking roller having a layer containing at least diamond-like carbon on the surface;
An endless fixing belt that is wound around a plurality of rollers including the temperature-uniforming roller, and whose belt surface moves with the rotation of the plurality of rollers;
A pressure roller that press-contacts the belt surface of the fixing belt and cooperates with the belt surface to sandwich and convey the sheet;
A heating unit for heating the fixing belt;
A fixing device.   The fixing device according to claim 12, wherein the fixing belt includes a metal conductive layer on a surface in contact with the temperature-uniforming roller. The fixing device according to claim 12, wherein the heat equalizing roller includes a heat pipe therein.

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